Clutch control mechanism



A. BREWER INVENTOR. [flames H Bnfwf/Q Filed April 28' 1932 CLUTCH CONTROL MECHANISM April-11, 1944.

Patented Apr. 11, 1944 UNITED i STATI-:s- PATENT "OFFICE A CLUTCH 0053114185: HECHANISH Charles A. Brewer, Norotonflelghtl, Gunn.,

to Philip J. Kury, Arveme signor of one-half This invention relates ingeneralto clutch con- `trol mechanism for automotive vehicles and in particular to a vacuum operated mechanism of this character operable with the closing of the throttle to disengage the clutch and automatically operable with the opening of the throttle to permit a reengagement of the clutch in such fashion as to accurately simulate the corresponding manual operation of the clutch.

It is the principal object of the invention to improve upon the vacuum operated clutch controlling mechalsm disclosed in the patent to Belcia No. 1,470,272, dated October 9, 1923. As disclosed in this patent, the operation, by the accelerator pedal, of a three-way control valve effects a uniform movement of the clutch pedal, which action, however, is undesirable inasmuch as too much time is`consumed in engaging the clutch.

To obviate this undesirable operation of the clutch control mechanism there is suggested automatically operable means, preferably independent of the aforementioned control valve, to insure a variable rate of clutch pedal movement whereby the pedal is moved relatively rapidly during the irst portion of its stroke and quite slowly thereafter and immediately prior to the actual engagement of the clutch plates. The total elapsed time consumed in effecting the clutch engagement is thus reduced to a minimum, thereby obviating the racing of the motor prior to clutch engagement and avoiding delay in accelerating the vehicle. In short, the mechanism suggested by the present invention serves to accurately simulate the conventional manual control of the clutch.

A further object of the invention is to provide means supplementing the aforementioned twostage control means, whereby the aforementioned elapsed time is varied according to'the mode of operation of the internal-combustion engine of the vehicle.

To the above end there is provided automatically operated means for controlling the clutch engaging function of the clutch mechanism, said means being variable in its operation according` to the degree of manifold vacuum of the internalcombustion engine.

Another object of the invention is to provide means, cooperating with a double-ended vacuum operated motor, for controlling the rate of movement of the piston of said motor, the mode of operation of said means and the consequent mode of operation of said piston being a function o! the degree of manifold vacuum, said means being rate movement of the trolled by angularly movable valvular means, the.

operable to control the degree of gaseous pressure in the suction or active side of the motor.

A further object is to provide a clutch controlling vacuum operated fluid motor, the rate of piston element of which is conlatter being controlled by the position of the piston within the motor, said valvular means cooperating with the aforementioned automatically operated means of movement of the piston .element of the motor in its clutch engaging function.

Yet another object of the invention is to provide a very compact power operated clutch control unit well suited for eld installation in automotive vehicles, the motor serving as a mounting for a plurality of control valves.

Other objects of the invention and desirable details of construction, such as the details of the several. valves, and combinations of parts will become apparent from the following description of a preferred embodiment, which description is taken in commotion with the accompanying drawing, in which:

Figure 1 is a diagrammatic view illustrating the essential elements ofthe vacuum operated clutch controlling mechanism constituting the invention;

Figure 1a is an enlarged detail view, partly in section and with parts broken away, o! one form of switch mechanisml which may be employed in the embodiment of Figure 1.

Figure 2 is a longitudinal sectional view of the combined motor and valve unit constituting the essential element of the mechanism; and

Figures 3 and 4 are sections taken respectively on lines 3 3 and 4 4 of Figure 2 disclosing details oi' part of the valvular mechanism for con-l trolling the engagement of the clutch.

Referring now to the embodiment of thel invention illustrated diagrammatically in Figure 1, there is disclosed a clutch pedal il) adapted to operate a conventional clutch, not shown. The pedal is adapted to be moved to its clutch disengaged position, shown in full lines in Figure 1, by a iiuid motor I2, a reciprocable piston I4 of. which is connected to the clutch pedal by a slip joint connection I6 permitting manual operation of the clutch without eiiecting corresponding movement oi' the piston. As shown, connecting means I6 comprises a rod 9, the enlarged balllike end 8 of which is retained in the hollow piston rod I6' by a tubular bushing l that threadedly engages the internal wall of said piston rod. It will be apparent that the effective length of to effectively provide a variable member serves as a valve end of the cylinder of the motor with an intake manifold 26 of the internal-combustion engine 22 of the vehicle. An electrically operated valve 24 serves to control the connection between the manifold and the motor to thereby control the operation of the latter.

The contro1 valve structure preferably comprises a solenoid winding 26 and a reciprocable spring pressed amature valve member 28, all housed within a two-piece casting 30 formingan end closure of the fluid motor. The armature member at each end thereof, one end 32 cooperating with a port 34 conrected with the manifold to provide an inlet or vacuum valve, and the other end 36 providing an atmospheric valve cooperating with a port 38, the latter communicating with a tubular conduit 40 rigidly supported on the motor casing at one end by the closure 36 and at the other end by a support or closure 42 forked at 44, Figure 3.

One end of solenoid 26 is connected by means of a lead 26a to a contact 46a of a suitable switch 46 and the other end thereof is connected by a lead 26h to one terminal of a suitable source of electric energy, such as a battery B. The other terminal of the battery and switch contact 46b are electrically connected through suitable ground connections. Contacts 46a and 46h are adapted to be bridged by a conduit plate 46c mounted on and insulated from the lower end of a rod 48a which is preferably pivotally secured to accelerator pedal 48, whereby switch 4 6 will be closed when the accelerator pedal is released. Accordingly, upon release of said pedal and consequent closing of switch 46, solenoid winding 26 is energized to open inlet valve 32. The atmospheric valve 36 is, of course, closed as the vacuum valve is opened. With the operation of the accelerator pedal and opening of the switch`46 a spring 56 serves to move the armature 28 downwardly, closing the inlet or vacuum valve 32 and opening the atmospheric valve 36, all of which will be described in greater detail hereinafter. 'I'he accelerator pedal 48 is preferably connected by a rod 52 with a butterfly operating lever 54 of the carburetor, a lost motion or slip joint 56 being provided in the connection between the rod and lever to insure an operation of the control valve 24 before the throttle is opened. The rod 52 is returned to its released position by a spring 51 and the lever 54 to a position for closing the throttle valve by a spring 51.

As is well-known in the art, a vacuum of some twenty inches of mercury is induced in the manifold at closed throttle by the pumping action of the engine pistons, and this evacuated condition of the manifold serves, by virtue of its connection with the clutch operating motor I2, to evacuate and energize the latter to disengage the clutch; therefore, with the disclosed construction the clutch is disengaged when and if the engine throttle is closed to thereby operate the valve 24.

Briefly reviewing the operation of the mechanism thus far described, release of the accelerator pedal serves first to completely close the throttle and the last increment of movement of the accelerator permits the switch 46 to be closed to energize the solenoid and open the control valve to disengage the clutch. Actuation of the' accelerator pedal effects a reversar of the above cycle of operations, the clutch being engaged as the engine speed is increased. In the clutch engaging operation of the motor atmosphere is permitted to reenter the motor via the duct or tube 40 to vthus permit the conventional clutch spring to ree'ng-age the clutch plates.

The invention is particularly directed, however, to means for automatically controlling the rate of clutch engagement, that is the rate of movement of the driving clutch plate as it moves toward the driven plate. Such control of the clutch in its engaging operation is desired in order to simulate the corresponding manual control of the clutch, and more particularly to effect an engagement of the clutch plates when the R. P. M. of the driving clutch plate is equal to or approximately equal lto that of the driven plate when and if the vehicle is in motion. It is furthermore desired to provide a very slow or slipping clutch movement of the driving clutch plate in starting the car from a parked condition or in reversing the direction of the car in backing up.

To the above end an automatically operable bleeder `valve member is provided within the aforementioned end closure 36. This valve comprises a flexible diaphragm 56 rigidly secured at its edges between the two parts of the closure. The flexible diaphragm is provided at its center with a hub portion 66, the 1atter provided with a threaded stem portion 62. To one end of the stem portion there is threadedly secured a nut 64 serving as a thrust member for a spring 66 interposed between the nut and a wall 68 of the outer or cap portion of the closure 30. One end of the stem is provided with a ball valve 10 adapted to Seat within and upon a valve port or seat 12, the latter providing communication between an atmospheric port 14, disclosed both in Figures 1 and 2, and a duct 16, the latter registering with the aforementioned port 38 leading to the interior of the motor. The closure 30 provides achamber 18, to the right of the diaphragm 58, which chamber is in communication with the vacuum supply port 34 via a duct 80. The operation of the aforementioned bleed valve will be described in detail hereinafter.

There is also suggested other valvular means for controlling the engaging movement of the clutch and cooperating with the aforementioned bleed valve. This 1atter valvular means preferably comprises a post or extension 82 secured to the piston I4 and adjustably housing a threaded screw member 84, the latter threadedly receiving a. cam member 86 relatively adjustable therewith. The cam member, with movement of the piston, is adapted to contact one end of a set.

screw 88, the latter being adjustably mounted in an arm 96 secured to a rotatable valve member 92 mountedupon one end of the tube 48. The -tube is provided with a slot 94 adapted to register with a slot 96 in the rotatable valve member 92. There is also provided an adjustable set screw needle valve member 98, the latter determining the rate of ai;` ow through a duct interconnecting the atmosphere with the interior of the tube 48.

Describing now the complete clutch engaging operation of the invention, a depression of the accelerator pedal serves to close the control valve 24, the atmosphere being permitted to enter the clutch motor via registered slots 94 'and se. The clutch engaging movement of the clutch pedal is thus initiated, the movement being uniform until the cam 86 contacts the set screw 88 to impart angular movement to the rotatable v the engagement of asaassa valve member 92, cutting oil communication between the atmosphere and the cylinder via. the slot 94. Subsequent movement of the clutch pedal is eiiected by virtue o1' the ingress of air via the relatively small bleed valve 98, the relatively small amount of air entering the cylinder through this valve insuring a relatively slow clutch plate contacting movement of the clutch pedal as is desired. y p

In addition to the variable clutch engaging movement effected by the aforementioned valves there is provided the control features of the aforementioned automatically operated bleed valve. The inner side of the diaphragm 59 of sure differential acting upon the diaphragm. the

atmosphere acting upon the left side, Figure 2, and the vacuum acting on the other side.

With operation of the electrically operated con'- trol valve 24 to engage the clutch. the throttle is opened, thereby diminishing the degree of vacuum, i. e., increasing the gaseous pressure in the intake manifold and tending to establish an equilibrium of forces acting on the diaphragm 58. The compressed valve spring 66 then functions to move .the ball valve ofi' its seat in proportion to the degree of manifold vacuum,lproviding a varied bleed of atmosphere from the opening 14 via valve opening 12 and duct 16 to thereby admit atmosphere at motor. It will thus be apparent that the movement of the clutch pedal is, in addition to the control affected by valves 92 and 98, also affected by the rate of ingress of air into the motor via the bleed valve, this rate of ingress of air being a direct function of the degree of manifold vacuum. With a relatively small opening of the throttle as in starting or reversing the automobile there is provided a relatively slow engagement of the clutch and with the further opening of the throttle after an operation of the changevariable rates tothe clutch' this valve is subjected to the vacuum of the in-c l5 speed transmission there is provided a faster engagement of the clutch by virtue of the increased inlux of atmosphere into the cylinder via the bleed valve. It will, therefore, be apparent that the total elapsed time in engaging the clutch is a direct function of the manifold vacuum which in turn is determined by the degree of throttle opening and the engine speed. This latter statement is true, inasmuch as the ingress of air to the clutch vcylinder via the control valves` 92 and 98 is constant and variable only by manual adjustment, the variation of time consumed in effecting either the rst or last stage of movement of the clutch being determined solely by the degree of manifold vacuum. The clutch may thus be engaged slowly in starting or reversing the car and more quickly after shifting the change-speed transmission into either second or high gears. If the operator should inadvertently tramp upon the accelerator pedal and thus quickly reduce the intake manifold vacuum the clutch would be engaged quickly and before the engine and connected driving clutch plate are speeded up to exceed the speed of the driven plate. It will also be apparent that a variation in the intake manifold pressure resulting from the clutch elements may cause the operation of variation in the rate of engagement of said elements in response to the efforts resilient means which normally bias the clutch elements toward engaged position.

There is thus skilled manual operation'of the clutch.

e one illustrative embodiment has been it is not my intention to limit the scope of the invention to that particular embodiment, or otherwise than by the terms of the appended claims.

I claim:

l. A clutch operating mechanism for an autointemal-comcontrol valve being clutch engaging opera` to the operation of said manifold.

5. In an automotive vehicle provided with an of the customary the clutch engaging operation oi the motor. said last mentioned means comprising a valve member automatically operable by differentials oi pressure between the atmosphere and the gaseous pressure of the intake manifold.

6. A clutch operating mechanism for an automotive vehicle provided with an internal-combustion engine and a clutch, said operating mechanism comprising a pressure differential operated motor operatively connected to the clutch, a control valve for said motor adapted to render the latter operative to effect the disengagement and control the engagement of the clutch, and valve means independent of said aforementioned control valve for controlling the engaging movement of the clutch, said valve means comprising a valve operable to eiect a lvariable engaging movement of the clutch and further comprising another valve cooperating with said last mentioned valve to vary the engaging movement of the clutch depending upon the degree of vacuum' in the manifold of the internal-combustion engine.

7. The combination with an internal-combustion engine adapted to create a vacuum, of a clutch connecting' the engine with a driven mechanism, a vacuum operable device for actuating said clutch, a control valve for said vacuum operable device, and a valve controlled by the vacuum created in the engine for controlling the engaging movement of the clutch.

8. The combination with an internal-combustion engine adapted to create a vacuum, of a clutch connecting the engine with a driven mechanism, a vacuum operable device foractuating said clutch, a control valve for said vacuum operable device, a valve controlled by the vacuum created in the engine for controlling the engaging movement of the clutch, and means for adjusting said last-named valve for adapting the operation thereof to an engine 'having various vacuum creating capacities.

9. The combination with an internal-combustion engine having a throttle controlled intake manifold, of a clutch connecting the engine with a driven mechanism, a vacuum cylinder, a piston in said cylinder operatively connected with said clutch, a control valve for said vacuum cylinder,

, an exhaust conduit leading from the cylinder to the intake manifold whereby the air is exhausted by the suction created therein, and means automatically controlled by the suction in said manifold for controlling the engaging movement of the clutch.

10. The combination with an internal-combustion engine having a throttle controlled intake manifold, of a clutch connecting the engine with a driven mechanism, a vacuum cylinder. a piston in said cylinder operatively connected with said clutch, a control valve for said vacuum cylinder, an exhaust conduit leading from the cylinder to the intake manifold whereby the air is exhausted by the suction created therein, and valvular mechanism actuated by the suction of the intake manifold for controlling the engaging movement of the clutch. A

11. Apparatus of the character described comprising a differential pressure power device having a movable member connected to an operating member of a motor vehicle clutch, a control device movable for establishing pressure differential in said power device to move the clutch elements to inoperative position and operative to establish pressure equalization in said power device, means automatically operative as the clutch .elements reach approximately the point of initial engagement for retarding the movement of suon elements, and a valve for controlling the rate of movement of the clutch elements into operative engagement in accordance with the rate of operation of the throttle of the vehicle engine in proportion to the engine speed.

l2. Apparatus of the character described comprising a power device connected to an operating member of a motor vehicle clutch, control means operable for rendering said power device operative to move the clutch to inoperative position and for releasing the clutch velements for movement toward operative position, and means for controlling the latter movement of the clutch elements comprising means connected to the aforementioned clutch operating member and operated thereby and further comprising means operative in accordance with the rate of operation of the throttle of the motor vehicle engine in proportion to the engine speed.

13. Apparatus of the character described comprising a power device connected to an operating member of a motor vehicle clutch, control means operable to render said power device operative to move the clutch to inoperative position and for releasing the clutch elements ior movement toward engaged position, `and means for varying the rate of clutch engaging movement of the clutch elements comprising means operable-to eieot a relatively rapid initial clutch engaging movement, and other means for completing the engagement of the clutch, said latter means being operative in accordance with the rate of operation of the throttle of the motor vehicle engine in proportion to the engine speed for controlling the rate of operation oi the clutch elements into engagement with each other through said last named means.

14, Apparatus of the character described comprising a power device connected to an operating member of a motor vehicle clutch, control means operable for rendering said power device operative to move the clutch to inoperative position and for releasing the clutch elements for movement toward operative position, and means for controlling the last mentioned movement of the clutch elements comprising control means operable in accordance with the rate of operation of the throttle of the motor vehicle engine inproportion tothe engine speed for controlling the rate of movement of the clutch elements into engagement wtih each other through said last named means.

15. Apparatus of the character described comprising a power device connected to an operating member of a motor vehicle clutch, control means operable for rendering said power device operative tov move the clutch to disengaged position and for releasing the clutch elements for movement toward engaged position, and means for controlling the clutch engaging movement of the clutch elements comprising means controlled by the rate of operation of the throttle of the motor vehicle engine in proportion to the engine speed for controlling the rate of movement of the clutch elements into engagement with each other through said last named means.

16. In an automobile with its clutch, the combination of a clutch actuator and mechanism for automatically operating 'said clutch actuator, said mechanism including a power cylinder having port means effecting quick movement of the actuator for the first portion of its movement in the direction of clutch engagement and slow movement of the actuator in the remaining pornism for automobiles vnism being provided with means for -on said diaphragm, one side tion of its movement in the direction of clutch engagement, and accelerator controlled means for said power cylinder adapted to control the rate of movement in said remaining portion.

17. In an automatic clutch operating mechahaving a throttle and throttle operating means, a source of vacuum, a vacuum cylinder and piston mechanism provided with means for vacuum connection and for air relief, and means for controlling the air relief associated with said cylinder and piston mechanism to afford relatively unrestricted relief during the first part of a stroke of the piston and controllable relief for the remainder of such stroke including valve means iniiuenced in its action by throttle operation.

18. yIn an automobile with its clutch, the combination of a clutch actuator and mechanism for automatically operating said clutch actuator, said mechanism including a fluid chamber having port means eiecting quick movement vof the actuator for the first portion of its movement in the direction of clutch engagement followed by relatively slow movement of the actuator in the direction of clutch engagement, and accelerator controlled means for said mechanism adapted to control the rate of movement following said first portions.

19. In an automatic clutch operating mechnism for an automobile having a throttle and throttle operating means, a source of vacuum, mechanism comprising a uid chamber and a member movable in said chamber, said mechavacuum connection and for air relief, and means for controlling the air relief associated with said mechanism to afford relatively unrestricted relief during the first part of a stroke of said member fol- 'lowed by relatively restricted relief, said means including valve means inuenced in by throttle operation.

v20. In an automatic: clutch operating mechanism for au automobile having a throttle and throttle operating means, a source of vacuum. mechanism comprising a vacuum chamber and a member movable therein, control valve means for said mechanism providing vacuum connection and air relief, valve means connected to be moved by said member for controlling the air relief, and valve means iniiuenced in its action by the operation of for controlling the air relief.

21. In clutch.` operating mechanism for automobiles, a source of vacuum, a vacuum cylinder and piston mechanism provided with means for vacuum connection and for air relief, and means its action for controlling the air relief including a housing,` a diaphragm therein, a valve operatively connected to the diaphragm for controlling air relief in proportion to the differential pressure acting of said diaphragm being subjected to atmospheric pressure and the other side of said diaphragm being subjected normally to less than atmospheric pressure, and yielding means for biasing the valve.

22. In combination with a motor vehicle having an engine for driving the latter, said engine having an intake manifold for supplying a combustible mixture of fuel and air thereto, of a clutch having a pair of relatively movable elements for connecting or disconnecting said engine and said vehicle, resilient means normally tending to hold said elements in frictional engagement with one another for driving said vehicle, uld pressure actuated means having a movable clutch operatsaid throttle operating means ing element adapted to separate said clutch elements in opposition to said resilient means and to permit the engagement of said clutch elements in response to the operation of said resilient means, and iiuid pressure actuated means responsive to variations in pressure in said intake manifold of said engine for changing the normal rate of engagement of said clutch elements in vresponse to the operation of said resilient means.

23.` In combination with a motor vehicle having an engine for driving t e latter, said engine having an intake manifold for supplying a combustible mixture of fuel and air thereto, of a clutch having a pair of relatively movable elements for connecting or disconnecting said engine and said vehicle, resilient means lnormally tending to hold said elements in frictional engagement with one ments in opposition to said resilient means and to permit the engagement of said clutch elements in response to the operation of said resilient means, and uid pressure actuated means responsive to variations in intake manifold prescontrol of the vehicle operator for establishing'a pressure diilerential in said poiver device to move said clutch to inoperative position, and cooperating meanscontrolled by encontrol the engaging movement of said clutch.

26. In an automotive vehicle provided with a ment of said clutch.

27. In an automotive vehicle provided with a drive shaft and an internal-combustion engine having an intake manifold and further provided with a clutch for controlling the connection between the engine and drive shaft, vacuum opervalve for said vacuum `mitting connection ated means for operating said clutch, a control operated means, and valve means for controlling the clutch engaging function of said clutch operating means, said valve means being automatically operable with changes in the degree of gaseous pressure within said manifold to thereby control the engaging movlment of said clutch and comprising a movable part operable by differentials of pressure caused by said changes in manifold pressure.

28. In an automotive vehicle yprovided with an internal-combustion engine having an intake manifold and further provided with a clutch, a throttle for controlling internal-combustion engine, and means for operating said throttle, vacuum operated clutch operating means connected to said clutch, said means comprising a iluid motor, a duid transbetween said motor and manifold, a motor control valve for controlling the iluid transmitting connection between said motor and manifold, means for operating said valve, and means for controlling the clutch engaging operationy of the motor in accordance with the pressure in the intake manifold, said control valve operating means junction with the aforementioned throttle operating means in such a manner that the control valve is operated prior to the operation of the throttle; whereby said control means is operated subsequent to the operation of the motor control valve.

29. A clutch operating mechanism for an automotive vehicle provided with an internal-combustion engine and a clutch, said operating mechanism comprising a pressure diilerential operated motor operatively connectedto the clutch, a 'control valve fory said motor adapted to render the latter operative to effect respectively the disengagement and engagement o! the clutch, and valve means independent of said aforementioned controlvalve for controlling the engaging movement of the clutch, said valve means comprising a valve operable to eiect a variable clutch 'engagement and further comprising another valve cooperating with said last mentioned valve to vary the engagement of the clutch depending upon the degree of vacuum in the manifold of the internal-combustion engine, all of said aforementioned valves being operative to control the gaseous pressure on one of the piston of said motor.

30. In a motor vehicle having an engine, a

clutch, a throttle and operating means for the latter, the combination comprising a power device including a pair of relatively movable elements forming a fluid chamber, means connecting one of said elements to an operating member of said clutch, means connecting said chamber to atmosphere, and valve means for controlling said last-named connecting means including a solenoid operated valve, the circuit to said solenoid being controlled by said throttle operating means, and a valve controlled in accordance with the rate of operation of said throttle in proportion to the engine speed.

-31. In a motor vehicle having an accelerator and a clutch, the combination therewith of a uid pressure operated power device connected to the clutch and capable of releasing it, a source of suction, means for connecting the power device with said source, means controlled by said accelerator for opening and closing said connecting means, and control means for said power device for varying the resistance of the latter the operation of said side being operable in conthe engaging movement of the clutch. said control means including pressure diilerential operated means controlled in accordance with the pressure in said source. e

82. In a motor vehicle having an accelerator `and a clutch, the combination of a power device connected to the clutch and capable of releasing it, a source of sub-atmospheric pressure, means connecting said power device to said source and to atmosphere, valve means for controlling said connecting means, electro-magnetic means for actuating said valve means, switch means operable by said accelerator for controlling said electro-magnetic means, and pressure differential operated valve means in said atmspherlc connecting means controlled in accordance with the pressure in said source.

33. In an automatic clutch operating mechanism for automobiles having a throttle and throttle operating means, a source of vacuum, a vacuum cylinder and piston mechanism provided with means for vacuum connection and for air relief and means for controlling the air relief associated with said cylinder and piston mechanism to afford relatively unrestricted relief during the first part of a stroke of the piston and controllable relief for the Vremainder of such stroke including valve means inuenced in its vaction `by manipulation of said throttle operating means.

84. In automatic clutch operating mechanism for automobiles having a throttle and an accelerating device controlling the throttle, a power device, a clutch actuator connected to the power device for operation thereby, main valve means for controlling said power device, means under control of the accelerating device for actuating said valve means, and other accelerating device controlled means for said power device operating to eifect variable relief upon actuation of the accelerating device.

35. In automatic clutch operating mechanism for automobiles having a, throttle and throttle operating means, a source of vacuum, a vacuum cylinder and piston mechanism, control valve means for said mechanism providing vacuum connection and air relief, valve means connected to be moved by the piston for controlling the air relief, and valve means controlled by the throttle operating means for controlling the air relief.

36. Apparatus of the character described comprising a power device connected to an operating member of a motor vehicle clutch, a control device operable for rendering saidpower device operative to move the clutch to inoperative position, and automatic means operative as the elements of the clutch approach operative position for re- Vtarding the movement of such elements, said control device including a member manually controllable for rendering said automatic means substantially ineffective for retarding the clutch elements.

37. Apparatus of the character described comprising a power device connected to a motor vehicle clutch having a normal bias to operative position, control mechanism for rendering the power device operative to move the clutch elements to inoperative position and to permit the clutch elements to return to normal position, and automatic means rendered operative as the elements of the clutch reach approximately the point of initial engagement for checking the movement of such elements, said control mechanism being subject to control independently of to u said automatic means for rendering the latter ineffective for substantially retarding the movement oi' the clutch elements.

38. In a clutch control device i'or motor vehicles, a power device operatively connected to the clutch and capable oi'releasing the same. means for connecting said power device, to a source oi' vacuum, and control mechanism comprising means for controlling said connecting means, automatic means responsive to the movement oi the clutch for controlling the degree of vacuum in bination, a cylinder, a clutch actuating member. a piston in said cylinder. a connection from said tion substantially at the point of initial engage ment for checking the movement of such elepedal connected to the throttle of the motor vehicle engine, and means operative upon depression of the laccelerator pedal from idling position i'or rendering said last named means operative.

42. Apparatus o! prising a power device operatively connected to return movement toward operative when the elements of the clutch reach an intermediate position i'or checking the movebeen checked mediate position, an accelerator pedal connected to the throttle oi the motor vehicle engine. and

means operative upon depression ci' the accelerator pedal from idling position `for rendering said last named means operative.

' CHARLES A. BREWER.

engaged position, meansl 

